The day before the state’s deadline for gaming applications, Town Administrator Louis Celozzi said he would be “shocked” if his community were in the mix because he had not heard in months from the developer who had proposed a casino there.

But David Nunes came through with an application and the $400,000 fee just minutes before the state’s 5 p.m. deadline Tuesday, becoming one of 11 contestants competing for three resort casino licenses and one slot parlor license in Massachusetts.

“And I was shocked. I almost fell off the couch. That’s the truth,” Celozzi said Wednesday.

Nunes, the developer of the proposed Crossroads Resort, did not return calls for comment last week, but the project he described to Milford officials months ago called for an $850 million complex that would feature a 176,000-square-foot gambling floor, a 350-room hotel, and 60,000 square feet of restaurants and retail shops.

As the host community, Milford would have a chance to vote on the project if it passes state muster. But surrounding towns worry they will have little or no say in the decision.

“We’re going to mobilize behind the scenes, and we’ll be putting all our ducks in a row and getting together an opposition effort,” said Ken Rockett, a Holliston resident and spokesman for Casino-Free Milford.

Over the past year, his group of organizers from Milford, Hopkinton, and Holliston established the website casinofreemilford.com, set up a Facebook page, and has collected more than 1,100 signatures on a petition against the casino.

“Our biggest issue is we feel that this casino is going into a neighborhood,” Rockett said. “There are at least 100 homes within about a quarter to a third of a mile from the property.”

But supporters of a Milford casino say they have solid arguments to make too, and urge everyone to reserve judgment until there are more details of what is to come.

“It’s all about jobs and bringing more employment base into the area,” said Bob Clemente, who runs two family-owned businesses in town. “It’s my opinion it would be a great thing for not only Milford but the entire area.”

He said a casino would drive more revenues to small businesses like his Purchase Street Market and Midtown Family Fitness and Racquetball Club.

“You need to look beyond the casino and you need to look at the effect on other businesses that will, by default, grow by having more people in the area willing and able to spend money,” said Clemente, a Milford resident. “The town will benefit and surrounding towns will benefit by an increased tax base.”

Beyond jobs, Milford would gain an estimated $8 million to $20 million annually in taxes and fees if a casino opens there, according to Clyde Barrow, director of the Center for Policy Analysis at University of Massachusetts Dartmouth.

But Crossroads faces serious competition from the two other proposals competing for the single casino license reserved for Eastern Massachusetts. The other applicants — Suffolk Downs in East Boston along with its partner, Caesars Entertainment, and Steve Wynn, who is proposing a casino on industrial land in Everett — bring marquee names to the competition, Barrow said.

Nunes has partnered with Bill Warner of Warner Gaming, which runs the Hard Rock Hotel & Casino in Las Vegas.

“Warner is a recognized name in the industry but not on the level of Caesars or Wynn,” said Barrow.

According to the Massachusetts Gaming Commission, which will ultimately award the licenses, the next step is to complete background investigations on all 11 applicants.

The Milford Board of Selectmen does not want to waste resources evaluating the idea until the state has given its preliminary approval, Celozzi said .

“I don’t think we get serious until Mr. Nunes and the other applicants are vetted by the gaming commission, and then he comes forward with a rock-solid proposal,” he said.

But Jay Marsden, chairman of the Holliston Board of Selectmen, rattled off a long list of possible problems: traffic, water, public safety, as well as proximity to the Twin River Casino in Lincoln, R.I., which is about 20 miles away and just got approval to extend its gaming from slots to tables.